Time to Shop for Some Bop in a Box : ***** ELTON JOHN “To Be Continued . . . “<i> MCA</i> : *** 1/2 THE BEE GEES “Tales From the Brothers Gibb: A History in Song 1967-1990” <i> Polydor</i>

How much of a favorite artist’s music do you want in one package--and how much are you willing to pay for it?

Those are the key questions facing consumers in the era of the boxed set--the record industry’s favorite new marketing strategy.

How, for instance, do five hours of Elton John sound to you--for about $60 for the CDs, a bit less for the cassette packages? Good idea or rip-off?

Those prices are steep for the casual fan, who would probably be satisfied with the traditional greatest-hits packages. For about $35, you can obtain 32 of John’s best-known songs by buying his three greatest-hits albums.

What do you get for the extra $25? Quite a bit: “To Be Continued . . . “ contains 37 additional songs, generally superior sound, and an illustrated, 40-page booklet that features comments by John and lyricist Bernie Taupin on their music and careers.

For pop historians or devoted fans, the sets make sense. Expect to quibble over a few song selections once you get past the parade of Top 40 hits, but also expect to be delighted by some bonus features--either hard-to-find or previously unavailable tracks--found in the best sets.

Among the surprises in “Continued”: a song recorded with the group Bluesology five years before the 1970 breakthrough with “Your Song,” the previously unreleased demo for “Your Song,” a live version of “I Feel Like a Bullet in the Gun of Robert Ford” and four new songs produced by Was (Not Was)’s Don Was.

The last, unfortunately, are not inspired, but the heart of the album serves as a warm, convincing profile of one of the most accomplished songwriting teams of the modern pop era and documents how brilliantly the records blended pop craft and rock energy and independence.

One reason that John in the ‘70s was the most successful recording artist since the Beatles was that he had a love and respect for pop music that infused almost every album with a sense of celebration and heart. To a remarkable degree, “To Be Continued’ captures that spirit.

The Bee Gees made a few records as good as the best of John’s or almost any other pop competitor’s, from the simple “To Love Somebody” to the marvelous, disco-era singles, including “Stayin’ Alive” and “Tragedy.” But the brothers Gibb lacked the consistency of vision to produce quality records on a continuing basis--as this four-disc, 80-song set reminds us.

It adds to the charm of the package that the Gibbs can look back on some of the failures with good humor. Regarding 1970’s “I’ll Kiss Your Memory,” Barry Gibb notes, “I think we’ve written a few good country songs in our time, although I’m not sure this is one of them.”

Albums are rated on a scale of one star (poor) to five (a classic).